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posted on June 15, 2012, 3:54 am
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A while back I inherited my Dads pretty clean 04, 1.6, 45k Meriva.
Shortly after getting it I noticed the (indicated) temperature would
often sit off the bottom of the gauge (so below 70 DegC), even at
prolonged motorway speeds. I confirmed the gauge readings with a
decent thermometer (and later an OBD reader and Android tablet).
The engine would (fully) heat up however in town / traffic etc and the
electric fan come on as expected. The issue wasn't really the running
temperature as such but if the engine running cold (especially during
over / high speed runs) might be negatively impacting on the mpg
(circa 31 across two tanks of petrol).
So, I first changed the temperature sensor as it was cheap and easy
and that made no discernable difference.
The next step was to change the thermostat but as that involved
removing the cam belt and associated gear I had that done at the same
time (as the car was 8 years old that was one of the criteria on belt
replacement).
So, we picked it up and took it for a run yesterday and according to
both the gauge and the Torque Pro OBD app it was running at a pretty
constant 88 Deg C (going up to 101 before the fan cut in and back down
to 96 when it dropped out again).
Now, the Torque Pro app has a much (much) slower 'Average MPG' display
so after maybe 30 miles of mixed driving we are only up to 29.5 mpg.
The instantaneous goes up to 150 odd on overrun. ;-)
So, well give it a bit of time to settle down and see if there is any
improvement in the real world mpg and if not I might have a closer
look at next doors 04 Focus 1.6.
Cheers and a gold star to all those who thought it might be the stat
re the cold running (Googling seems to show many people being told
'They all do that Sir', especially by the main dealers!).
Cheers, T i m
p.s. Strangely the old stat opened at 82 DegC when I tested it on the
hob?
Re: 250 quid thermostat but worth it.
It might not do the same when under the normal working pressure of a
cooling system. And they're generally more like 90c these days.
--
*Parenthetical remarks (however relevant) are (usually) unnecessary *
Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.
Re: 250 quid thermostat but worth it.
Hmm, good thought ... although I think I remember them testing this
way in the past and I think they are still 'wax pellet' design aren't
they?
Ah, well, that might explain it. Someone kindly gave me the exact
rating for this Meriva when I first asked about this but something
seems to have changed re this Agent (or whoever serves Usenet for VM)
but I only see about a month of posts now (I'm sure it used to hold
older posts even when purged off the server)?
Ah ha! ... I've just looked at the old stat again but this time under
my illuminated magnifier and it reads '92 / 107 o' so, if that (as you
say) reflects the range in DegC that the stat starts to open and till
it's fully open (?), then it is indeed opening way too early. Still
not at the sort of temperatures it was in the car (more like
maintaining a running temp of sub 70) but early none the less.
Oh well, that's even better then. Both the stat and belt actually
needed changing, you would do the tensioner in any case and I've done
the water pump as well as it was the right thing to do. At least if it
doesn't make any real-world difference to the mpg then should be a
positive selling point.
Cheers, T i m
p.s. And thanks to Chris re the heads up on the Android OBD app
'Torque' and reader. As a mate once said, 'You can manage what you can
measure' and that combination lets you watch live a whole bunch. (It
was obvious the difference between the instant mpg figures on the
Corsa (50) and the Meriva (30) for example.)
Re: 250 quid thermostat but worth it.
[...]
Heh! My first car was a 10 year-old 1954 A40 Somerset; if you compared it
with a 10 year-old car now, it was a heap of crap.
I changed the 'stats on lots of cars in the past, but not one since the
early 80's.
Chris
--
Remove prejudice to reply.
Re: 250 quid thermostat but worth it.
Thermostats often used to get stuck closed, which I put down to the lack of
anti-freeze. Most cars used to only have anti-freeze put in at the first
frosts and it was out again in early spring. The first car I used on the
road never had any antifreeze, I drained it after use and filled it with hot
water before, put the handle in and gave it a turn (knackered battery). It
was actually the most likely vehicle to get up and running on a freezing
morning, so I would often be asked to go and start other people's cars with
jump leads. I have no idea if that car had a thermostat in at all. Many
cars didn't, relying on cardboard in front of the rad if it got really cold.
Re: 250 quid thermostat but worth it.
I still remember one guy at work in the '70's who (in very cold weather)
lifted the bonnet and put a blanket over the warm rad in the morning to
keep the heat in. Until one day he started it up in the evening without
removing it, and put a fan blade through the rad. Direct belt drive, no
clutch in those days!
Re: 250 quid thermostat but worth it.
[...]
I believe that in general, most things are better made now. Extended life
of components can also come from better quality control, as well as
improved design.
My last car, which I had for 10 years, had one cooling hose changed as a
precaution in its life. If I hadn't changed it, I doubt it would have
caused a problem, but I'm cautious. A car from the 50's, 60's, or 70's
would most likely have had every coolant hose replaced in 10 years, and
the top hose several times.
Most sensible folk with cars from that era would carry a spare 'fan'
belt. It was generally considered good practice to change them every
other year, *if* they lasted that long. Again, the car I ran for 10 years
had the auxiliary belt replaced with the cam belt at 100k miles, but it
looked as if it would have lasted another 100k.
Also, cooling system designs have changed significantly. Thermostats used
to mostly fail closed, which meant you *had* to replace (or discard) it.
They generally fail open now. The cooling fan was mechanically driven;
now, it's a thermostatically controlled electric fan, which tends to
disguise a sub-optimal thermostat.
Chris
--
Remove prejudice to reply.
Re: 250 quid thermostat but worth it.
I managed to use 'Torque Pro' Heads-Up on the 8" tablet tonight and it
displayed a cozy 86 DegC at 65 mph, even with the heater on. ;-)
MPG slowly creeping up to around 33.
Just like to say how impressed I am with the Torque app. Best £2.95
I've spent in a long time. ;-)
Cheers, T i m
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